Manufacture of smokeless powder



209. CLASSIFYING, Str'AriAi uw, AND ASSORUNG SULIDS.

Feb. 27, 1945. B. rRoxLER MANUFACTURE OF SMOKELESS POWDER Filed Feb. 2, 1945 Bern/)arf Fox/er l INVENTOR.

MA V2.

ATTORNEY Ouml.. mmIZEaw Patented Feb. 27, 1945 MANUFACTURE F SMOKELESS POWDER Bernhart Troxler, Kenvil, N. J., assignor to Hercules Powder Company, Wilmington, Del., a cor. poration of Delaware Application February 2, 1943, Serial No. 474,443

21 Claims.

This invention relates to an improved method for manufacturing propellent smokeless powder, and more particularly to an improved method for recovering the excess solvent from, and the drying of, single base smokeless powder. y

It is well known by the art that smokeless powder manufacture includes the following steps: The dehydration of the raw material, nitrocellulose or reclaimed smokeless powder; the colloid ing of the dehydrated material with a solvent or solvents, for example, an ethyl ether-ethyl alcohol or an acetone-ethyl alcohol mixture; the forming of the colloided mass into strands by pressing through one or more dies; the cutting of these strands into short lengths called grains; the treating of the grains to remove the excess solvent; the drying of the treatedgrains; thescreening of the grains to remove clusters and foreign material and the blending of the dry grains to produce a uniform product.

In the above process the steps of dehydration, colloiding, pressing, cutting, and blending have been developed to a high state of efficiency and comparative safety but the step of processing the grains to remove the excess solvent, the step of drying the grains, and the step of screening of .the grains, at present, from a standpoint of eillciency, economy, and safety show many disadvantages.

Now in order to produce a smokeless powder that will give satisfactory ballistics, it is necessary to control the amount of total volatile matter, retained in the grains, within very definite limits. Such limits are determined by the type of powder and the ballistics required. Therefore, the removal of the excess solvent and moisture fromthe grains is of the utmost importance in` the manufacture of an acceptable powder. These two' steps also have an economic effect on the process as the :time required and the equipment needed for recovering the excess solvent and for the drying of the powder have a very definite bearing on the per pound cost of-the completed powder.

The art originally placed the powder grains in small batches in a dry house after the cutting operation and by forcing hot air through the mass drove the solvents from the grains. It is" obvious that this was a very expensive operation as the solvents were lost. At present, the method of removing and recovering the solvents from the grains includes placing the powder grains in a solvent recovery system that consists of a number of rectangular boxes or bins that have air-tight covers and are equipped with means of circulating heated air through'the mass of;

grains and past condensing coils that remove the solvent vapors picked up by the air upon passage through the powder. The system provides for the continuoustcircula-tion of the air with alternate heating, pick up of vapors, and the removal of vapors and this process of circulation is continued until they solvent content of the grains is reduced'Y to a low per cent. There are means provided in the system to remove all condensed vapors to a storagel tank where they await recovery by rectification. The reduction of the solvent content of? the powder grains by this method cannot be carrieilloutto the desired-lowv percentage and, therefore, itis necessary to further treat the grains'i'n what 4iricjminonly termed by the art a water-dryfsystemy ,The `water-drying of the grains consists of treatgi'the grain'svwith hot water for a suillcient period" toeect the reduction of solvent contentflt'o the desiredper cent. "f

From .the water-dryiope'ratiom the powder is taken to dry houses where it' isa spread on trays and heated by forcdl'al'r: drafts `until dried to the total volatile -content desired." The dryhouses are expensive and the drying procedure is hazardous. The powderfisl' loaded' inf wooden trays that are positioned in the dry house to allow air circulation which must be controlled in regard to temperature and speed, as high temperatures cause excessive deterioration and the possibility of fire, while excessively fast drying caused by rapid circulation causes uneven drying.

From the dry-houses the powder must be placed in storage or taken direct to a screen house to remove all clusters and foreign material. From the screening operation the powder is stored or taken directly to the blender where a substantially uniform product is produced.

It will be apparent to those skilled in the art that each of the described processes requires at least two handlings of the powder and further that each time powder is handled there are losses and the operators areexposed to the inherent hazard of handling explosives. It is also well acceptedthat excessive handling ofv material and` the use of batch processes are very expensive and undesirable.

Eiiorts to perform the same operations in one or more vessels of large capacity have not been attended with any degree of success. When a mass of solvent-wet smokeless powder grains is.

loaded into a vessel of large capacity for solvent recovery or watery drying ofthe grains, at least' two factors must beo'ed with. The weight of the last portions of the charge added to the ves-` AND Assimil-intox its.

' CROSS REFERENCE sel presses down on the lowermost portions of the mass and tends to form agglomerates or clusters of grains which resist the desired drying and solvent removal steps. Of equal, Vif not greater, importance is the formation of individual grains which depart from the uniform grain shape and size; i. e., distortion of the grains. This may occur as part of or apart from clusteringr or agglomeration of a plurality 'of grains. These clusters have to be screened out and reprocessed. Furthermore, there is a distinct tendency for the mass of the powder grains to present non-uniform resistance to the treating fluids. This results in non-uniform drying and channeling of the drying fluids through.. the mass at points of least resistance. This, in turn, may and frequently does cause the same distortion of individual grains and the same clustering or agglomeration which may also result from the mere superimposed weight of the mass of grains on the lower portions of the mass. Since it is the goal of the smokeless powder manufacturers to produce ammunition, every grain of which is uniform in size and chemical constitution, any treatment which forms non-uniform grains,4 or causes distortion, is a departure from that goal.

It is the object of this invention to provide an improved method for the solvent recovery andv drying of colloided smokeless powder. It is the particular object of the invention to provide a.

method of recovering solvent from. solvent-wet smokeless powder in large batches without causingv appreciable distortion.. clustering or agglomeration. of the individual grains. Another object ofthe invention .comprises an` improved method for carrying out the water-dryvv treatment of smokeless powder and the final drying oftheI solvent-free grains. It is also an object of the invention to provide means whereby the solvent recovery step, the water-dry treatment and the air drying of smokeless powder may be Vaccomplished in large bulk in a. singlepiece of ap.- paratus. thereby avoiding excessive handling of thepowder. Other objects of the invention are to provide ameans for recovering a higher percentage of the excess solvent in the powder andv to reduce the time required for the steps of treatment of solvent-wet smokeless powder to give the finished powder. Production of smokeless powder having uniform ballistic properties in large volume economically, rapidly and safely are the prime objectives of the invention.

It has now been discovered, in accordance with this invention,-that smokeless powder grains resulting from colloiding a mixture, comprising nitrocellulose with a solvent, pressing the co1- loided nitrocellulose into strands and cutting the nitrocellulose strands into grains of smokeless powder of any desired size, may be 'uniformly processed in large bulk to produce uniform grains without distortion, clustering and agglomeration by performing certain procedural steps and preferabhz by utilizing certain preferred and go to make a charge of uniform ballistic properties.

The above ends are accomplished by charging a colloid mixture of nitrocellulose and a solvent in the form of grains of any desired size or shape either slowly or in small increments into a tank in which a heated, gaseous medium capable of removing the excess solvent is maintained, the loadingof the tank being carried out in such a manner as to establish in the tank a bed of smokeless powder grains having uniform resistance throughout the mass to the passage of fluid therethrough, the heated, gaseous medium serving to volatilize a sufficient amount of the solvent as the bed is being built up to cause hardening of the individual grains, thereby preventing any substantial distortion of the grains during the loading of the tank, and subseciuentliv removing the bulk of the solvent by passing the heated non-reactive gas capable of removing the excess solvent through thebed of powder, treating'the powder with aliquidcapable of removing the residual solvent to remove residual solvent and then drying thepowder.

In the preferred method of carrying out the improved process the solvent-wet smokeless powdergrains are loaded into a tank onto a foraminous or perforated support or screen which is inclined from the horizontal at an angle which does not vary greatly from the angle of repose of a. mass of theA smokeless powder grains of the type being treated. It has been found desirable types .of apparatus. It has been found that it .is

tocontrol the rate of loading of the said grains into the tank so as not to create ay mass of such great depth as. would causethe distortion, cluster. ing or agglomeration from the sheer weight of the upper grains resting upon the lower grains lmtil asuieient amount of the solvent has been removedY from the powder already in the tank to prevent distortion, clustering or agglomeration.

of the grains in the tank by the weight of the grains of a subsequent increment. The direct rem'. sult accomplish by this slow or incremental;

loading of the grains into a-heated, gaseous medium is the preliminary hardening of the grains and the establishment of a resistance to the distortion and clustering which would otherwise take place when further increments are superimposed on the earlier ones. 'I'his incremental or slow addition of the charge to the treating vessel containing a heated, gaseous medium forms an important part of this invention.

One of the main features of my invention, however, comprises adding a sufficient amount of the smokeless powder grains to be treated onto the,

sloping foraminous or perforated plate or screen so that a body of grains isbuilt up which by virtue of the slopeY of the support. has its lower surface disposed at an angle which does not vary greatly.` from the angle of repose and which has its'upper surface likewise disposed at the angleof repose of the grain in the mass. vI have found it desirableA to charge the grains into the vessel and shunt them uniformly by a. suitable baffle so asta dispose them uniformly around the inner wall ofthe vessel, i. e., peripherally. Tile grains so disposed then drop onto vthe upper portion of the-sloping screen or support and by gravity tend to slide downthe support or screen. As further additions of the grains are madein this manner, thgrains build up on the support in a body which has. both its upper and lower surfaces .close to, if not identical with, the angle of repose of the grains in the mass. Thus, there is created4 pool UH H01 throughout and substantially uniform resistance throughout to the passage of the fluids which will be used for removing solvents from the grains. It will be understood that the exact angle of repose will vary depending upon the size of the individual grains, depending upon the apparent density of the individual grains and depending upon the surface characteristics of the grains. This variation must be taken into consideration and correlated along with the nature of the treating fluid, the pressure at which it is introduced into the vessel and the resistance of the body of grains to the passage of the drying iiuid therethrough. A very important feature of my invention is the loading of the powder grains in the manner described just above while simultaneously subjecting the grains to solvent removal uids, particularly a heated non-reactive gas, thus achieving preliminary and progressive hardening of the grains to prevent distortions and clustering.

After removal of the bulk of the solvent from the bed of smokeless powder grains by means of the heated non-reactive gas in the manner described above, the residual solvent must be removed. This is accomplished by completely cov ering the powder grains with hot water and circulating the hot water to maintain the proper temperature. This water-dry treatment need not be carried out in the same tank but is desirably carried out with the powder grains disposed at substantially the angle of repose as in the solvent recovery treatment with the heated non-reactive gas. The water-dry treatment is preferably carried out with the tank open to the atmosphere so as to allow all vapors to escape to the air. The water-dry treatment is continued until the residual solvent is removed from the grains to a point that complies with the particular specication being used, after which the powder is ready to be air dried.

The air drying may be accomplished conveniently by draining the water from the tank and then passing heated air or other non-reactive gas through the powder, preferably with the tank open and exhausting the drying air to the atmosphere. The powder at the end of the drying operation has the proper moisture content and is, of course, quite hot. To prevent the handling of the hot powder, cold air or other non-reactive gas may be blown through the powder until the powder temperature is approximately equal to room temperature.

While it is highly desirable to carry out the solvent recovery step, the water-dry treatment and the air-dry treatment in the single tank, it will be appreciated that the demand for vaporproof and waterproof tanks in the plant may be pressing, in which event both the water-dry and air-dry treatments may be carried out in a separate tank or tanks different from that used for the solvent recovery treatment. An advanta-geous feature accomplished by the use of a separate tank for the water-dry and air-dry treatments is that the particularly hazardous solvent recovery step of the process may be isolated from the following treatments. Another advantage is that the tanks for the water-dry 'and air-dry steps need not be constructed so as to be vaporproof. Where more than one tank is used for the above three processing steps, it is desirable that the tanks for the water-dry and airdry treatments be similarly constructed so as to provide means for disposing the powder grains in a bed having-uniform resistance throughout the mass to the passage of fluid therethrough. The charging of the powder grains from the solvent recovery tank to the water-dry tank may be carried out in any desired manner since the danger of distortion, clustering or agglomeration of the grains is no longer present after removal of the bulkof the solvent. Alternatively, the airdry step may be performed in a dry house where the powder is dried by placing it on trays.

This changing of the powder to another piece of apparatus for water-drying and for air-drying is often desirable when the number of vaporproof and waterproof tanks are not suilicient for the desired production or when they cannot carry the peak periods of production cycles. The use of extra tanks or of dry houses has been found to be more economical than the use of vaporproof tanks in rush periods, but the preferable' means of air-drying the powder is in the tank in which it has been water-dried.

The removal of the water-wet powder from the tank where it was water-dried may also take place after the powder has been partially dried in the tank, for example to about 10 or 20% moisture; and this procedure is sometimes desirable as the powder grains handle more easily as the moisture content is reduced. The nal drying down to, for example, about 1 or 2% moisture, may then be carried out in another tank or in a dry house where the moisture content may be reduced slowly to the exact percentage desired.

The procedure of drying in equipment other than the tank which is used for the solvent recovery and water-dry is especially desirable when it is necessary to produce a batch of powder of a definite and specific moisture content for use in blending in order to obtain the desired ballistics.

The powder is dried to the desired moisture content, removed from the air-drying equipment, which may either be a tank or a dry house, screened and sent to the blending house. The screening of the powder may be conducted in connectionfwith the air-drying operation, or it may be conducted in a special piece of equipment.

The invention may be exemplied and practiced in a variety of manners. It may be suitably practiced by utilizing the apparatus represented in the accompanying drawing. 'I'he figure indicates diagrammatcally, with parts in section, the preferred embodiment of the apparatus .of this invention for the manufacture of smokeless powder. The apparatus shown is set forth more specifically and claimed in my copending application, Serial No. 474,442, led on February 2, 1943.

To facilitate an understanding of the method of treating smokeless powder with the apparatus of this invention, a detailed description of the apparatus used will be made with reference to a .part of the gure.

The tank I, which is shown in section, is of a novel design that permits the carrying out of the solvent recovery, water-dry, and air-dry process stepsV without disturbing the powder charge once it has been placed in the tank. The tank l, pref-'- erably of relatively large size such as to hold several thousand pounds of powder, has an opening 2 at the top which is closed by a cover 3 that is shaped to fit into the water seal trough 4 around the opening 2. The cover 3 is further designed in the shape of a funnel preferably having 'a slope of about 40 and the funnel has an opening 5v located directly above the center ofthe -tank I. The opening 5 is closed by suitablemeans, not shown, such as with a rubber or wood-- to allow inspection of the inside of the tank while section 9 is stationary and extends to within about six inches of the side of the tank and thus causes the even distribution of the powder within the tank and toward the inner periphery of the wall of the tank. The slope of the conical spreader preferably has a slope of about 35. This peripheral loading may be accomplished by providing an annular opening instead of the spreader but thev spreader is most convenient in operation..

The tank I also has a false bottom or support I which is shaped like an inverted cone. This support provides for the removal of the powder charge through valve I2 centrally located in the bottom of the tank and concentric with the axis of the cone. The cone-shaped false bottom preferably is of smooth metal which is perforated or of screen material rolled toprovide a smooth surface. The openings in the plate or screen are of a size which prevents Athe powder grains from passing through but which will allow the free circulation of a uid medium throughout the tank. It will be understood that the perforations or the mesh may be altered to suit the type of powder being processed. The cone-shaped bottom is designed so that the angle or slope is preferably about 30 and is between about 25 and about 33. This angle of slope is important as it corresponds closely to the angle of repose of powder grains and, therefore, provides a mass of powder which has a uniform thickness and a uniform resistance to the passage of fluid media that may be used to remove solvent to dry the powder grains. I have found that it is preferable that the supporting bottom or screen be inclined at an angle of between about 28 and 30 although angles between about 25 and about 33 operate successfully. Any major departure between this range of inclination will cause the mass of powder dropped onto the inclined surface to build up in a non-uniform body which will influence the resistance of the mass to fluids passing therethrough and make the resistance non-uniform.

I prefer that the cone-shaped support I0 be fabricated from a material which will not spark. For this purpose, copper, aluminum or plastics may be employed. I also prefer that the support or bottom have as many small openings as possible in order to facilitate uniform passage of the fluid through the support and through the supported body of powder grains. I have found that if the holes are about .025 inch to about .050 inch in width, the desired purpose will be accomplished satisfactorily. Plates having openings or screens having a mesh within this preferred range will satisfactorily support powder grains which are from about 0.2 to about 0.5 inch in diameter and from about 0.5 to about 2.0 inches in length. My greatest preference is for a bottom or support fabricated from a perforated plate but the support may. if desired, be fabricated from screen of the desired mesh if the screen be rolled to give it a smooth surface.

The valve I2 in the bottom of the tank may be of any type suitable for removing the powder grains from the tank. 'I'he type shown consists of a plunger I4 attached to a rod I5, acting through a guide I6, that extends to within a few inches of top point 6 of the spreader 1. The valve I2 is, therefore, easily operated, from the I3 under valve I2 may be used to control the rate of emptying the powder grains from the tank. It may be of conventional design.

` The tank should be of vaporproof and waterproof design and may be fabricated from aluminum, copper, or the like, or may be a lined wooden tank. While ferrous alloys may be used, it-is not desirable to include any metal from which sparks may be struck due to the explosive nature of the powder charge. Further, the tank is equipped with the necessary air and water valves to carry out the processes and the method of making such connections will be obvious to those skilled in the art.

In the apparatus just described. suitable bames or rings (not shown on the drawing) disposed at various points around the shaft I5 of the valve I 2 lmay be employed. Such bames or rings, if utilized, would serve to divert any powder grains which tended to collect in the center of the tank back toward the inner periphery of the walls of the tank so that the uniform depth and fluid resistance of the powder on the support I0 is preserved. The same result may be accomplished by the enlarged discharge valve I4 shown in the drawing. Y

There now follows a description of the process for treating the powder in the described apparatus of this invention. The grains of powder from the cutting machine may be processed, in the single tank I described hereinbefore, to the point where they are ready for screening prior to blending, or they may be placed in the tank for any single step or combination of the steps of solvent removal, water drying, air drying, cooling and screening. The process with reference to the figure is carried out by loading tank I, via opening 5, with powder grains from the cutting machines. The spreader 1 distributes the powder evenly within the tank I and also aids in breaking up any clusters of powder that may have formed while the powder grains were in the container at the cutting machine.

The tank I is preferably lled with powder to about the bottom of the spreader 1 by the slow or incremental loading procedure heretofore mentioned. During such slow or intermittent charging of the tank, the three-way valve I1 is set to allow the circulation of a heated gaseous medium, air, or an inert gas, preferably exhaust gases, from fan I8 through heater I9 down through the powder in tank I, out through the three-way air valve I1 to the condenser 20. The hot gas from the heater I 9 absorbs solvent vapor from the -powder and substantially all these absor-bed vapors are removed by the condenser 20 afterwhich the air is recirculated through the system to pick up more solvent vapors. 'I'here are means provided in the system to remove all condensed vapors to a storage tank where they await recovery by rectification. The circulation may be intermittent during the charging of the tank I for example. thev fan I8 is cut otI while powder is being dumped into the tank but when the tank is lled to the desired height the circu lation of air is continuous until the solvent ccntent is reduced to a low percentage. If the tank is filled above the edges of the spreader, the top section 8 thereof may be removed to aid circulation. The powder grains loaded into the tank normally are brought to the tank from the cutting machines in containers, i. e., roving cans, holding about 50-100 pounds of powder grains. 'I'he speed with which the tank is filled depends entirely upon the rate of cutting powder, and this filling operation thus may be an intermittent process that may require only a few hours or may extend over a period of two days or even longer.

It is well known that the old method of solvent recovery resulted in clustering and distortion of the powder grains. This was due to the fact that it was not practical to operate the solvent recovery process while filling the old type apparatus. Thus, the old method allowed solvent to condense within the apparatus which softened the grains and due to the weight of the powder those softened grains clustered and were distorted. With the solvent recovery method and apparatus of this invention, clustering and distortion are not experienced because the hot air or other inert gas may be circulated until the apparatus is brought up to the operating temperature before any powder is put in the'tank and an atmosphere capable of removing solvent may always be maintained within the tank. Further, the air circulation is continuous during the tank charging period except for the various short intervals of time that powder is actually being dumped into the tank, which short intervals do not affect the removal of solvent as the air, though not circulating, is capable of absorbing solvent until circulation is again started, therefore, removal of solvent from the powder starts as soon as the first increment enters the tank, thus causing the grains to harden which eliminates the clustering and distortion of the grains that was experienced in the method known to the art.

Clustering and distortion also resulted from a lack of uniform resistance to the gaseous medium being circulated, causing channeling in the powder mass. The apparatus of this invention with the conical bottom having a slope equal to the angle of repose of the powder causes the powder, when peripherally loaded, to assume a position which causes a uniform resistance to be established.

After removal of the solvent by uniform gas circulation the residual solvent is removed and this is accomplished by closing the three-way air valve I1 and adjusting the three-way water valve 2l to allow the tank I to be lled with hot water or other inert liquid. The tank I is lled to an overflow pipe 22 above the level of the powder, and the valve 2l then so adjusted to keep sumcient water circulating tol maintain the proper temperature. During the water-dry operation, the cover 3 is removed to allow all vapors to es.. cape to the air. This water-dry operation is continued until the residual solvent is removed from the grains to a point that complies with the particular specification being used, after which the powder is ready to be air-dried.

The air-drying of the powder may be accomplished by' draining the water from the tank I through valve 2| and then so adjusting valve I1 that hotv gases from the fan 23 may be blown through heater 24 into tank I and through the powder. The hot gas uniformly dries the powder because the resistance'of thev powder mass is substantially equal due to the loading of the powder upon the false bottom sloped at the-.an gle of repose of the powder. The cover' 3 is left open and the drying air is exhausted to the atmosphere. The powder at the end of the drying operation has the proper moisture content and is, of course, quite hot. To prevent the handling of hot powder, the heater 24 is turned oil' and cold gases blown through the powder until the powder temperature is approximately equal to room temperature.

The powder is now ready to be removed from the tank and this is accomplished by opening the valve I2 in the bottom of tank I and allowing the powder to run freely from the tank. The cone-shaped false bottom II) which has an angle of slope substantially equal. vto the angle of repose of the powder and has a smooth surface aids the dumping of the tank as will be apparent from the drawing. A screen may be located just below the valve I2 whereby the powder is screened as the tank is emptied and the valve I2 may be so regulated that the amount of powder leaving the tank I may be conveniently screened and packed into bags. The. powder after being bagged is ready to be sent to the blender or to storage and the tank I fromwhich it was removed is ready for another charge of powder.

The heaters I9 and may be fed with steam and may be automatically. regulated to maintain the desired gas temperatures during the. solvent recovery and air drying operations. The fans I8 and 23 should be of sulcient capacity to emciently remove the solventsV and water from the powder in the desired lengths of time. It will be obvious thatv the fan 23 for drying, the4 powder will be of much greater capacityv than the fan I8 used to circulate air for removing the solvent vapors.

The three-way valves II and 2l may be standard air and water valves or a series of connections may be made to perform the function of these two valves.

The screen 25 is positioned under the dumping valve I2 and is designed and placed to obtain effective screening of whatever type of powder is being manufactured. It is desirable to have a screen holder that allows changing of screens easily if a variety of granulations are to be manufactured. The screen, as will be obvious may be equipped to remove large and small particles of powder and may also be equipped with any suitable means for aiding in bagging the powder. A screen used in screening powder is preferably not of the vibrating type and, therefore, the screen used in this invention has been placed at an angle and the. powder allowed to flow over it by gravity.

In the specific description given hereabove, using the described apparatus, the solvent recovery. water-dry and air-dry steps have been described as being carried out successively in the sarde vessel, the air-dry powder being discharged onto a suitable screen and then packaged for storage or shipment. This, as has been stated above, is a virtue of my preferred type of apparatus, namely, that the apparatus permits these three steps to be carried out successively without handling and without. removal from the vessel until the air-drying, 'of the powder has been achieved. The combining of the four operations of solvent recovery, water-dry, air-dry and screening in one tankLand; particularly the, rst

der charge with a liquid capable of removing the residual. solvent; then with a gaseous medium capable of removing said liquid and then discharging said' smokeless powder.

.4. A method for the manufacture of substantially completely colloided smokeless powder which includes the steps, in the order named, of colloiding a mixture comprising nitrocellulose with a. solvent; pressing the colloided nitrocellulose` into strands; cutting the nitrocellulose strands into grains of smokeless powder of any desired size; charging the said smokeless powder grains into a tank by a succession of increment charges until said tank contains the powder charge desired; treating said powder charge with a heated gaseous medium capable of removing excess solvent during said charging whereby the individual grains of the increment charges are hardened to a degree which prevents substantial grain distortion by the charging of the successive increment charges; then treating the powder charge with a liquid capable of removing the residual solvent; then with a gaseous medium capable of removing said liquid; then with a gaseous medium to cool the powder charge; and then discharging said smokeless powder.

5. A method for 'the manufacture of substantially completely colloided smokeless powder which includes the steps, in the order named, of colloiding a mixture comprising nitrocellulose with a solvent; pressing the colloided nitrocellulose into strands; cutting the nitrocellulose strands into grains of smokeless powder of any desired size; charging the said smokeless powder grains into a tank by a succession of increment charges until said tank contains the powder charge desired; treating said powder charge with a, heated gaseous medium capable of removing excess solvent during said charging whereby the individual grains of the increment charges are hardened to a degree which prevents substantial grain distortion by the charging of the successive increment charges; then treating the powder charge with a. liquid capable of removing the residual solvent; then with a gaseous medium capable of removing said liquid; then with a gaseous medium to cool the powder charge; and then discharging said smokeless powder onto a screen to obtain a. smokeless powder of the desired grain size.

6. 'I'he method of manufacturing substantially completely colloided smokeless powder which includes the steps, in the order named, of colloiding a mixture comprising nitrocellulose with a solvent; pressing the colloided nitrocellulose into strands; cutting the nitrocellulose strands into grains'of smokeless powder of any desired size; charging the said smokeless powder grains into a tank; treating the charge with a heated gaseous medium capable of removing the excess solvent; said powder charge being charged into said tank slowly while said heated gaseous medium is maintained therein to remove excess solvent whereby the individual grains ,become hardened, and substantial distortion thereof by the charging is prevented; then with a liquid capable of removing the residual solvent; and discharging` the wet smokeless powder, and drying said discharged powder.

7. A method for the manufacture of substantially completely colloided smokeless powder which includes the steps, in the order named, of colloiding a mixture comprising nitrocellulose with a solvent; pressing the colloided nitrocellu loseidts` strands; cutting the .nitrocellulose strands. into grains of smokeless powder of any desired size; charging the said smokeless powder grains into a tank by a succession of increment charges until said tank contains the powder charge desired; treating said powder charge with a heated gaseous medium capable of removing excess solvent during said charging whereby the individual grains of the increment charges are hardened to a degree winch prevents substantial grain distortion by the charging of the successive increment charges; then treating the powder charge with a liquid capable of removing the residual solvent; and discharging wet smokeless powder, and drying said discharged powder.

8. The method forthe manufacture of substantially completely colloided smokeless powder which includes the steps, in the order named, of colloiding a mixture comprising nitrocellulose with a solvent; pressing the colloided nitrocellulose into strands; cutting the nitrocellulose. strands into grains of smokeless powder of any desired size; charging the grains slowly into a tank and onto a fluid permeable supporting surface inclined at substantially the angle of repose for the grains to form a bed of grains having uniform resistance to the ilow of uid therethrough; passinga heated gaseous medium capable of removing excess solvent downwardly through` the grains in the tank during said charging into said tank, thereby effecting. sumcientfhardening of the individual grains to prevent substantial distortion thereoi' by the charging of subsequent additions of grains; passing a heated non-reactive gas capable of. removing excess solvent through the bed of grains to remove solvent therefrom; discharging the substantially solvent-freeA grains; treating the grains with a.1iquid capable of removing the residual solvent; and drying the wet grains.

9. The-method for the manufacture of substantially completely colloided smokeless powder which includes the steps, in the order named, of colloiding a mixture comprising nitrocellulose with a solvent; pressing the colloided nitrocellulose into strands; lcutting the nitrocellulose strands into grains of smokeless powder of any desired size; charging the grains slowly into a tank and onto a fluid permeable supporting surface inclined at substantially the angle of repose for the grains to form a bed of grains having uniform resistance to the flow of uid therethrough; passing a heated gaseous medium capable of removing excess solvent downwardly through the grains in the tank during said charging into said tank, thereby effecting sumcient hardening of the individual grains to prevent substantial distortion thereof by the charging of subsequent additions of grains; passing a heated non-reactive vgas capable of removing excess solvent through the bed of grains to remove solvent-.,therefrom; treating the grains with a liquid capable of removing the residual solvent; discharging the substantially solvent-free grains; and drying the wet graiis.

10. The method for the. manufacture of substantially completely colloided smokeless powder which includes the steps, in the order named. of colloiding'a mixture comprising nitrocellulose with-a solvent; pressing the colloided nitrocellulose into strands; cutting the nitrocellulose strands into grains of-smokeless powder of any desired'size; charging the grains slowly into a tank yand onto ailuid permeable supporting surfminclinecbat substantially the angle ofrepose for the grains to form a bed o! gmini having unifominesistance to the new of fluid passing a heated gaseous medium capable of removing excess solvent downwardly through the grains in the tank during said charging intol said tank, thereby electing spil-leicht hardening of the individual grains to prevent substantial distortion thereof by the charging of subsequent additions of grains; passing a heated non-reactive sas capable oi removing excess solvent through the bed ot grains to remove solvent therefrom; treating the grains with a liquid capable of removing the residual solvent; drying the wet grains; and discharging the substantially solvent-free grains.

11. The method for the manufacture of substantially completely colloided smokeless powder which includes the steps, in the order named, of colloiding a mixture comprising nitrocellulose with a solvent; pressing the colloided nitrocel'- lulose into strands; cutting the nitrocellulose strands into grains of smokeless powder of any desired size; charging the grains slowly into a tank and onto a fluid permeable supporting surface inclined a-t substantially the angle. of repose tor the grains to form a bed of grains having uniform resistance to the flow of fluid therethrough; passing a heated gaseous medium capable of removing excess solvent downwardly through the grains in the tank during said ch-arg- .i

ing into said tank, thereby effecting suimcient hardening of the individual grains to prevent substantial distortion thereof byv the charging of subsequent additions of grains.; passing a heatednoni-reactive gas capable' of removing excess -1 solvent through the bed of grains to remove solvent therefrom.; treating grains with a liquid capable of removing the residual solvent; drying the wet grains; cooling the dried gra-uis; and

discharging the substantially solvent-free gra-ins.

12. The method for the manufacture of substantially completely colloided smokeless powder which includes the steps, in the order named, of colloiding a mixture comprising nitrocellulose with a solvent; pressing the coiloided nitrocellulose into strands; cutting the nitrocellulose strands into grains of smokeiess. powder of'any desired size; charging the grains slowly into a tank and onto a huid permeable supporting surface inclined at substantlally the angle of repose for the grains to form a bed ci grains having uniform resistance to the flow of uid therethrough; passing a hearted gaseous medium ca pable of. removing excess solvent downwardly through the grains in the tank during said charging into said tank, thereby effecting sumcient hardening' of the individual grains to prevent substantial distortion thereof by the charging of subsequent additions ofgrains; passing a heated non-reactive gas capabie of" removing excess solvent through the bed of grains to remove solvent thereirom; treating the grains with a liquid capable of removing the residual solvent; drying the wet grains; cooling the dried gralns' and discharging the' substantially solvent-free grains onto a screen to obtain a smokeless powder of desired grain size.

13. In a process of removing solvent from coliloided smokeless powder grains, the stepgwhicli comprise charging a mass of the said smokeless powder grains slowly into-a tankv and onto a tlui'd permeable supporting surface located adjacent the bottom of said tank andl inclined at substsm-l tiall'y the angle of repose of the 'grainsin the mass; passing a heated gaseous medium' capable of removing excess solvent downwardiy through the smokeless powder grains in the tank dimm; said charging into said tank; distributing the grains in said tank in the form of a bed of smokeless powder grains having uniform resistance throughout the mass to the passage of fluid there through, thereby effecting suliicient hardening of the individual grains in the tank to prevent substantial distortion of said grains by the cha-rgi-ng of subsequent additions of grains; and passing a heated nom-reactive gas capable of removing excess solvent through the bed of smokeless powder grains built up in said tank by said charging method`l to remove solvent therefrom.

14. In a processI of removing solvent from col loided smokeless powder grains, the steps which comprise charging a mass of the said smokeless powder grains slowly into a tank and onto a fluid permeable supporting surface located adjacent the bottom of said tank and inclined at substantially the angle of repose of the grains in the mass; passing a heated gaseous medium capable of removing excess solvent downwardly through the smokeless powder grains in the tank during said charging into' said tank; distributing the grains in said tank in the form of a bed of smokeless powder grains having uniform resistance throughout the mass to the passage of fluid therethrough, thereby effecting suiiicient hardening of the individual grains in the tank to prevent substantial distortion of said grains by the charging of subsequent additions of grains; and passing heated air capable of removing excess solvent through the bed of smokeless powder grains built up in said tank by said charging method to remove solvent therefrom.

15. In a process of removing solvent from col'- loided smokeless powder grains, the steps which comprise charging a mass of the said smokeless powder grains by a succession of increment charges into a tank and onto a iluid permeable supporting surface located adjacent the bottom of said tank and inclined at substantially the angle of repose of the grains in the mass; passing a heated gaseous medium capable of removing excess solvent downwardly through the smokeless powder grains in the tank during said charging into said tank; distributing the grains in said tank in the form of a bed of smokeless powder grains having uniform resistance throughout the mass to the passage of fluid therethrough, thereby effecting sufficient hardening of the' individual grains in the tank to prevent substani tial' distortion of Said grainslby the charging of subsequent additions or grains; and passing a heated non-reactive gas capable of removing excess solvent through the bed of smokelesspowder grains built 'up in said tank by' said charging method to remove solvent therefrom.

l`6. In a process of removing solvent from co1- loided smokeless powder grains, the steps which comprise charging a mass of the' said smokeless powder grains by a successionl of increment charges into al tank and ontol a fluid permeable supporting surface locatedv adjacent the bottom of said tank and inclined at substantially angle or repose of the grains inthe mass; pass# ing a heated' gaseous medium capable ofA removing excess solvent downwardly throughb the smokeless powder gra-insin. the tank duringsaid charging into said tank; distributingrt'he grains in saif'dtank in the form of a bed of smokeless powder' grains having uniform resistance f throughout the mass to -tihepassage ofin'uid there# through, tliereby effecting sufciertt hardening ci the individual grains in the tank to prevent substantial distortion of said grains -by the charging of subsequent additions of grains; and passing heated air capable of removing excess solvent through the bed of smokeless powder grains built up in said tank by said charging method to remove solvent therefrom.

1'Z. The method for the manufacture of substantially completely colloided smokeless powder which includes the steps, in the order named, of fcolloiding a mixture comprising nitrocellulose with a solvent; pressing the colloided nitrocellulose into strands; cutting the nitrocellulose strands into grains of smokeless powder of any desired size; charging a mass of the grains by a succession of incremeht charges into a tank and onto a fluid permeable supporting surface inclined at substantially the angle of repose for the grains in the mass to form a bed of grains having uniform resistance to the ow of uid therethrough; passing a heated gaseous medium capable of removing excess solvent downwardly through the grains in the tank during said charging into said tank, thereby effecting suicient hardening of the individual grains to prevent substantial distortion thereof by the charging of subsequent additions of grains; passing a heated non-reactive gas capable of removing excess solvent through the bed of grains to remove solvent therefrom; vdischarging the substantially solventfree grains; treating the grains with a liquid capable of removing the residual solvent; and drying the wet grains.

18. The method for the manufacture of substantially completely colloided smokeless powder which includes the steps, in the order named, of colloiding a mixture comprising nitrocellulose with a solvent; pressing the colloided nitrocellulose into strands; cutting the nitrocellulose strands into grains of smokeless powder of any desired size; charging a mass cf the grains by a succession of increment charges into a tank and onto a fluid permeable supporting surface inclined at substantially the angle of repose for the grains in the mass to form a bed of grains having uniform resistance to the flow of fluid therethrough; passing a heated gaseous medium capable of removing excess solvent downwardly through the grains in the tank during said charging into said tank, thereby effecting sufcient hardening of the individual grains to prevent,

substantial distortion thereof by the charging of subsequent additions of grains; passing a heated non-reactive gas capable of removing ex cess solvent through the bed of grains to remove solvent therefrom; 'treating the grains with a liquid capable of removing the residual solvent; discharging the substantially solvent-free grains; and drying the wet grains.

19. The methodl for the manufacture of substantially completely colloided smokeless powder which includes the steps, in the order named, of colloiding a mixture comprising nitrocellulose with a solvent; pressing the colloided nitrocellu' lose into strands; cutting the nitrocellulose strands into grains of smokeless powder of any desired size; charging a mass of the grains by a succession of increment charges into a tank and onto a uid permeable supporting surface inclined at substantially the angle of repose for thegrains inthe masstoformabedofsrains having uniform resistance to the ow of fluid therethrough; passinga heated gaseous medium capable of removing excess solvent downwardly through the grains in the tank during said charging into said tank, thereby effecting 'sufficient hardening of the individual grains to prevent substantial distortion thereof by the charging of subsequent additions of grains; passing a heated non-reactive gas capable of removing excess solvent through the bed of grains to remove solvent therefrom; treating the grains with a liquid capable of removing the residual solvent; drying the wet grains; and discharging the substantially solvent-free grains.

20. The method for the manufacture of substantially completely colloided smokeless powder which includes the steps, in the order named, of colloiding a mixture comprising nitrocellulose with a solvent; pressing the colloided nitrocellulose into strands; cutting the nitrocellulose strands into grains of smokeless powder of any desired size; charging a mass of the grains by a succession of increment charges into a tank and onto a uid permeable supporting surface inclined 'at substantially the angle of repose for the grains in the mass to form a bed of grains having uniform resistance to the flow of uid therethrough; passing a heated gaseous medium capable of removing excess solvent downwardly through the grains in the tank during said charging into said tank, thereby effecting sufllcient hardening of the individual grains to prevent substantial distortion thereof by the charging of subsequent additions of grains; passing a heated non-reactive gas capable of removing excess solvent through the lbed of grains to remove solvent therefrom; treating the grains with a liquid capable of removing the residual solvent; drying the wetgrains; cooling the dried grains; and discharging the substantially solvent-free grains.

21. The method for the manufacture of substantially completely colloided smokeless powder which includes the steps, in the order named, of colloiding a mixture comprising nitrocellulose with a solvent; pressing the colloided nitrocellulose into strands; cutting the nitrocellulose strands into grains of smokeless powder of any desired size; charging a mass of the grains by a succession of increment charges into a tank and onto a fluid permeable supporting surface inclined at substantially the angle of repose for the grains in the mass to form a bed of grains having uniform resistance to the flow of uid therethrough; passing a heated gaseous medium capable of removing Vexcess solvent downwardly through the grains in the tank during said charging into said tank, thereby eiecting sufficient hardening of the individual grains to prevent substantial distortionV thereof by the charging of subsequent additions of grains; passing a heated non-reactive gas capable of removing excess solvent through the lbei of grains to remove solvent therefrom; treating the grains with a liquid capable of removing the residual solvent; drying the wet grains; cooling the dried grains; and

desired grain size. f

BERNHART TROXLER. 

